4speed into 5 speed (280i)

[Graham]

Is this a difficult swap to replace the 5 speed type 9 with a 4 speed.

will the existing prop and mounts line up ?

I just want to experiment on the racer as the 5 speed ratios are full of holes...

[taz turbo]

Graham, I tried to post a reply changing the four speed to the five speed some time ago and failed (the size of the reply maybe). I shall mail you that reply if you read it backwards (sort of) it should make some sense.

[Graham]

that would be great


cheers

G

[jeff m]

Five to four eh.
This page may help
www.fotango.com/p/eba00371901f00000001.jpg
Jeff

[Graham]

jeff m said:

Five to four eh. This page may help www.fotango.com/p/eba00371901f00000001.jpg Jeff

probably but its too small to read

[jeff m]

Graham,
Sorry about that.
Basically, it says they are the "N" type 5 speed and "E" type four speed.
The mountings are modified slightly.
I'm not sure exactly what "slightly" means.
Quoting from manual
Externally the 5 speed differs from the 4 speed by having an itermediate plate between the transmission housing and the extension housing and a metal tag bearing the corrosponding code

It also says that the (N Box) 5th gives an 18% reduction in rpm.

I have a E box on mine next time I go under it I could measure the prop for you.
Jeff

[Graham]

Thanks Guys it looks like it should be straight forward enough ( as if anything on the wedge is straight forward)

Jeff i dont suppose you know your diff ratio? my owners manual listys it as 3.54 for both which carnt be correct....


Looks like i'll be playing with diffs and gearboxes over the winter, as long as i can fix the over fueling problem first...

oh yes and ditching the handbrake for a line lock and another repaint ( too many tyre wall marks on the current paint job )


G

[jeff m]

Graham,
From owners handbook.
3.07:1 It seems to be the same for 4speed and the auto which is three speed. (I suppose someone has one!)
Gear ratios for the "e" type from the manual are:
1st 3.163:1 7.01 mph/1000rpm
2nd 1.942:1 11.43
3rd 1.412:1 15.73
4th 1.000:1 22.18
All on 14" wheels.

For comparison the n type ratios are
1st 3.36
2nd 1.81
3rd 1.26
4th 1.00
5th 0.825
Jeff

[taz turbo]

Graham, In the mail I sent you it stated that the five speed box is 'slightly shorter' than the four speed item, to quantify this, its about 10mm. When I swapped 4 to 5, I retained the original prop, it just enters the box less. I don't know if the prop for the four and five speed cars were the same as delivered from the factory, (and if there was a difference, which prop my car has on it now as new five speed then changed to four???) if there was a difference you could be into shortening your prop. Let me know which route you decide to take, I have a four speed box at the back of the garage.
Chris.